Micro-optics involves mounting a lens on a surface smaller than a pinhead and condensing the full power of complex optical devices into a package smaller than a fingernail.
Microlens Arrays. Image Credit: Avantier Inc.
How Small Can Optics Get?
Video Credit: Avantier Inc.
A micro-optic is an optical part or array between a few micrometers and a millimeter in size. As manufacturing developments make them more accessible to consumer requirements, miniature optics are increasingly central to contemporary manufacturing practices.
Once the exclusive domain of specialized defense and research projects, economical micro-optics are now ubiquitous in consumer products ranging from fiber-optic communication systems to smartphones and biomedical devices. In this article, Aventier explores some examples.
Biomedical Applications of Micro-Optics
Biomedical sensors are an important application of micro-optics. The core of these sensors is generally a micro-opto electromechanical system, which integrates micro-optics, minute electronic components, and other mechanical parts to build a solid, lightweight system for integration into the human body.
The MOEMS used in biomedicine are composed of micoroptics combined with electronics and mechanical components. Image Credit: Avantier Inc.
These systems should be manufactured with care for maximum strength, durability, stiffness, and fatigue resistance. They should additionally be optimized for their specific function and the setting they will be found in the body.
A 3D intraoral scanner utilized within the back, used on photonics micro-electronic-mechanical systems (MEMS) technology, may be utilized to map the 3D image required for precise dental restoration.
Back pain is challenging to diagnose, but a Fiber Bragg Grating sensor may be incorporated into the intervertebral disc to improve understanding of pressure distribution in the intervertebral disc and improve clinical diagnostics of disc strain.
Another application arises with the inner eye pressure that causes glaucoma. Increased intraocular pressure can be observed with a micro-sized optical implant utilizing a flexible photonic crystal membrane.
A micro-optic sensor can be used to determine the cause of back problems. Image Credit: Avantier Inc.
Manufacturing of Micro-Optics
Some micro-optical components are created similarly to their non-micro equivalents, although their relatively small size presents distinct challenges and necessitates additional care during manufacturing.
The small beam collimator lenses for laser diodes are an example of micro-optics typically manufactured via traditional approaches. These minute lenses may be one or two millimeters in diameter.
Traditional approaches make manufacturing the minute parts required for transmitting optical data impractical. A single optoelectronic chip might include microlasers, minute photodetectors, and various lenses or beam collimators.
A manufacturing technique utilized for these minute microlenses is photoresist reflow. A photoresist material is deposited on a circular area with an exceedingly small diameter, usually in tens of microns. When the device is subjected to heat, the photoresist melts. Surface tension allows the melted photoresist to have a well-defined surface and almost spherical curvature.
Replication approaches, including injection molding, hot embossing, and UV casting, involve manufacturing a master structure and then mass-producing a large quantity of identical minute optics.
Soft lithography, or microcontact printing, is another possibility for microplastic manufacture. This approach applies lithograph to optical materials like a wafer, and surface tension provides the smooth aspheric surface as desired.
Nanoimprint lithography is a type of soft lithography that utilizes UV light and special stamps to print lens patterns onto a prepared optical polymer material. This approach makes it possible to manufacture thousands of lenses on a single eight-inch substrate.
If more flexibility is required, direct laser writing may be considered This approach can be utilized to manufacture complex three-dimensional microstructures, and the possibilities it may generate are currently under exploration.
Most of these minute micro-optics are not typically produced and sold individually. They might be placed directly into their optical microsystems, merging into MEMS with distinct functions.
They may additionally be produced in the form of one- or two-dimensional arrays. When appropriate, laser-based processes may be utilized to insert a single microlens on the end of an optical fiber or other micro-component.
single microlens on the tip of a optical fiber. Image Credit: Avantier Inc.
This information has been sourced, reviewed, and adapted from materials provided by Avantier Inc.
For more information on this source, please visit Avantier Inc.